Switch device



Dec. 19, 1961 E. J. LEIMKUHLER SWITCH DEVICE 5 Sheets-Sheet 1 Filed Feb.4, 1960 FIG.

ATTORNEYS Dec. 19, 1961 E. J. LEIMKUHLER SWITCH DEVICE 5 Sheets-Sheet 2Filed Feb. 4, 1960 FIG. 2.

INVENTOR Edward J. Leimkuler yynnefly'ngen.

ATTORNEYS Dec. 12, 1961 w. DE FLIGUE 3,013,136

' ELECTROMAGNETIC RELAY Filed Jan. 18, 1960 5 Sheets-Sheet 3 l I I 13a6, 26 /a5 43 Dec. 19, 1961 E. J. LEIMKUHLER SWITCH DEVICE 5 Sheets-Sheet4 Filed Feb. 4, 1960 INVENTOR Edward J.Leimkuhler ATTORNEYS Dec. 19,1961 E. J. LEIMKUHLER SWITCH DEVICE 5 Sheets-Sheet 5 Filed Feb. 4, 1960INVENTOR EdwurdJ.Leimkuhler 119; Zin er:

ATTORNEYS BYWy'n United States Patent Office 3,014,135 Patented Dec. 19,1961 3,014,136 SWITCH DEVICE Edward J. Leimkuhler, 2910 MontebelloTerrace, Baltimore 14, Md. Filed Feb. 4, 1960, Ser. No. 6,717 13 Claims.(Cl. 307-64) My invention relates to an apparatus for automaticallyconnecting an electrical load to a second or emergency source of supplywhen the preferred or regular source of supply fails.

More particularly, my invention relates to an apparatus responsive to afailure of a predetermined condition or voltage failure of a preferredsupply to connect the electrical load to an emergency supply. Myapparatus is particularly adapted for electrical installations whichrequire a high degree of service reliability. Hospitals, publicbuildings, military establishments and the like are a few examples ofareas in which my invention may be utilized.

There are in use today numerous types of apparatus capable of performingthe operation for which my invention is designed. The industry foryears, however, has searched for a system of the required high standardof reliability capable of being manufactured and installed at a lowercost. The requirements to be met by such a system are well establishedin the industry. Most important, is the requirement of faultlessoperation with safety.

My invention is designed to include a minimum number of operating parts,to provide an easily movable and installable unit in presently existingcircuit interrupter arrangements, to enable periodic testing withminimum down-time and engineering complications, and to provide a unitwhich may be manufactured and installed at a reasonable cost.

When installed my apparatus is connected to the usual circuitinterrupters or switches which are capable of being manually operated.Circuit interrupters without operating handles can be easily adapted foruse with my apparatus.

Switch means enable the selective connection of a load with thepreferred supply or an emergency supply; a plurality of emergencysupplies can be utilized with suitable modifications. Transfer meansresponsive to a predetermined condition such as failure or radicalchanging of preferred voltage accomplishes the change-over as will bedescribed. Fluid powered means, preferably gas though hydraulic systemsmay be used, are used, a fluid driven preferred ram driving thepreferred switch and a fluid driven emergency ram the emergency switch.

To prevent change-over when a voltage fluctuation has a short life, atime delay means is included which delays flow of fluid through the gassupply system for a predetermined period of time, which is adjustable.

A solenoid controlled gas valve responds to the voltage fluctuation andcontrols gas flow to the preferred ram which includes a piston andcylinder, the preferred switch being connected to the piston. Suitablecontrols are provided for sequential actuation of the similar emergencyram. Further, as will be explained, my invention can be employed toautomatically as well as manually return the load to the preferredsupply upon return of power thereto either by paralleling the suppliesor by opening the emergency switch and then closing the preferredswitch.

When the manual return system is used only one electrical device isutilized in the switch change-over apparatus. The apparatus ismechanically reversible by simple relocation of the operating units;this reversibility feature permits continued use of the same transferdevice if supply feeders are reversed.

Other important objects and advantageous features of the invention willbe apparent from the following description and accompanying drawings,wherein, for the purposes of illustration herein, a specific embodimentof this invention is set forth in detail, and wherein:

FIG. 1 is a perspective view of my apparatus including portions of thepreferred feeder operating rod and the emergency feeder operating rod;

FIG. 2 is a perspective view similar to FIG. 1 with the operating rodsin their other positions and with the rams disconnected therefrom andtilted to a horizontal position for inspection and testing;

FIG. 3 is a schematic view showing the apparatus of FIGS. 1 and 2connected to the electrical system;

FIG. 4 is a schematic view of an embodiment of my invention providingautomatic return to preferred supply by paralleling the two supplies;and

FIG. 5 is a schematic view of another embodiment of my inventionproviding automatic return to preferred supply by first opening theemergency supply and then closing the preferred supply.

Referring now to FIGS. 1, 2, and 3, it will be seen that the apparatusof my invention includes a fluid operating system, the pneumatic or gassystem shown being preferred. A frame 70 is provided which includes abase 71 on which are mounted two operating rams 20 and 21 throughpivoted connections 72 and 73 which enable each ram to assume therequired angular attitude during actuation of the operating rods 74 and75. A support 76 is also provided at the base for a bottle 1 of gas,this bottle having a cut-off valve and a pressure regulator 2, the gasthen passing through the main gas supply system 60 to a main gas valve 4which, in the preferred embodiment, takes the form of a three-waysolenoid operated valve. This valve 4 as seen in FIG. 3 is electricallyconnected to the utilization voltage, this being the voltage supplied tothe load such as a hospital. On failure of utilization voltage thesolenoid will be released and the valve 4 will open.

The term three-way valve when used in this application defines a valvewhich allows downstream passage from one conduit to another, stopsupstream passage between the lines, and provides when closed for ventingof back pressure present downstream of the valve through a vent 90 (FIG.3).

The gas preferably then flows past a manual vent valve 3 to a time delaymeans 8 which delays activation of the rams a predetermined time toprevent change-over of switches due to only split second voltagefailure. This time delay means 8 includes a variable orifice 5adjustable by a knob, a gas reservoir 6 downstream thereof, followed bya three-way pilot valve 7, the vent 90 to atmosphere being responsive toback pressure upon closing of the pilot valve 7 being provided to ventthe cylinders and the lines. Gas flows from the time delay means 8 tothe upper end of preferred ram 20 and the piston therein is forceddownwardly with air venting through outlet 91. When the preferred ram 20reaches its lowermost open position, actuator 10 mounted on the ram 20engages three-way sequence valve 9 to allow gas to flow through the maingas supply system 60 to the lower end of emergency cylinder whereby theemergency ram 21 is forced upwardly to close the switch and connect theload to the emergency supply. 7

It will be noted in FIGS. 1 and 2 that the frame 70 includes a backplate 77 to which the preferred actuation arm 78 and the emergencyactuation arm 79 are pivotally mounted through angle brackets 80.Mounting holes 81 are provided in the back plate 77 for attachment ofthe apparatus to foundation bars, not shown. Any suitable technique ofanchoring the apparatus may be used. The preferred operating rod 74 andthe emergency operating rod are pivotally mounted about midway along thelength of the operating arms 78 and 79 and the rams 20 and 21 arepivotally mounted near the outer end por- Lions. Suitable removable pinsheld by locking rings may be used to facilitate disassembly. Sockets 83are provided at the ends of both arms '78 and '79 for receiving a leverto enable manual switching.

OPERATION Assuming loss of voltage from the normal or preferred supplydue to failure, the system will function as follows:

(i) Solenoid valve l will open, permitting gas to flow into the main gassupply system as.

(2) Gas pressure is immediately available to pilot valve 7 but cannotpass therethrough until a predetermined time elapses for the gas to passthrough variable orifice 5 and gas reservoir 6 whereby suilicientpressure is built up over the spring biased piston in pilot valve 7 tocause downward movement thereof and open the pilot valve to permit gastherethrough. The spring indicates schematically the force which must beovercome.

(3) When pilot valve 7 opens, gas ilows through the lay-pass line 25 ofthe time delay means 8 to closed threeway sequence valve Q and to theupper end of the preferred ram Ell which is attached to the circuitinterrupter or switch 10%? of the preferred supply. Upon downwardmovement of the preferred ram 2 9, actuator 19 opens sequence valve uponthe ram reaching its open position at the end of its downward stroke.

(4-) When valve 9 opens, gas flows to the lower end of the emergency ram21 causing the emergency ram 21 to move upward and thereby closing theemergency switch ltd and energizing the load circuit, thus restoringutilization voltage to gas valve 4.

(5) Restoration of utilization voltage causes gas valve l to close andshut of; the flow of gas in the main gas supply system till. Theresidual gas in the rams and gas lines will automatically vent toatmosphere through the vent ill in pilot valve 7', and the vent 93 insolenoid valve 4.

When the preferred supply becomes available again, the operator maymanually change-over the switches 1-61; to to reconnect the load to thepreferred supply. All manual switching operations, except one, may bedirectly performed by an attendant without regard to the automatictransfer device. The one exception occurs only if both sources of supplyfail. The device will then operate needlessly and fill the system withgas pressure which cannot vent to atmosphere through valve 4 or pilotvalve 7 because utilization voltage is not restored. Under suchcircumstances the system may be vented manually to atmosphere throughvent valve 3.

The apparatus is applicable to operations of all circuit interrupterdevices with manual operating handles. With suitable modifications, itcan be adapted to operate the controls of circuit interrupters Withoutoperating handles.

FIGURE 4 Apparatus for automatically returning the switches to normalcondition by paralleling the preferred supply with the emergency supplyis shown schematically in FIGURE 4-. Similar portions of FIGURE 4 toFIGURES 1, 2 and 3 carry similar numerals. This apparatus enablesautomatic return without interrupting the load circuit.

It will be noted that the main gas supply system 60 is similar to thatpreviously discussed and also includes a solenoid operated three-waystop valve 16 upstream of the previously discussed time delay means 8,valve 16 being normally closed and openable upon failure not of load orutilization voltage but of preferred supply voltage.

A secondary gas supply system 110 is also provided to supply the powerfor return of the rams to normal position, this system 11% being shownin pneumatic parallelism with the main system 69. A secondary gas valve17 is placed upstream of a solenoid operated control valve which is inturn upstream of a time delay means 48 which is similar to time delaymeans 8.

The secondary gas valve 17 is normally open and closes '11 upon failureof utilization or load by means of the electrical connections shown.

The control valve 15' is electrically connected to a standardmicro-switch 12 which connects the solenoid of the valve 15 to thepreferred supply voltage transformer 120 when the emergency ram 2-1 isin closed position placing the emergency switch 101. in closedcondition. A knee action micro-switch 13 is provided for actuation bythe emergency ram 21 when it is returned to open position to pulse thecontrol. valve 15 and cause valve l5 to close. The other elements of theapparatus are the same as FIGURE 3. Assuming loss of utilization or loadvoltage associated with failure of the preferred source of supply, thetransfer system will function as follows:

(l) Valve 4 and valve 16 will open permitting flow of gas through themain gas supply system 66.

(2) Gas pressure is immediately available to closed pilot valve "1 butgas cannot pass through it until sulficient time elapses (time delay)for gas to pass through variable orifice 5 and gas reservoir 6 andthence open pilot valve 7 to permit flow of gas through it.

(3) When pilot valve 7 opens, gas pressure becomes available to closedvalve 9 and to ram 20 attached to rod '74 and switch in the preferredsupply. Ram 20 will move downward transmitting corresponding motion toopen the attached circuit interrupter 1% in the preferred supply. Whenthe ram 20 reaches the end of its downward stroke and open position,mechanical actuator 10 will cause valve 9 to open.

(4) When valve 9 opens, gas pressure becomes available to ram 21attached to rod 75 and switch 101 in the emergency supply. Ram 21 willmove upward transmitting corresponding motion to close the attachedcircuit interrupter ltll in the emergency supply and restore loadvoltage to valve 4 and reenergize the load circuit.

(5) Restoration of load voltage will cause valve 4 to close and shut offthe liow of gas. The residual gas in the rains 2d, 21 and gas linesbeyond valve #2- will automatically vent to atmosphere through vents inpilot valve '7 and gas valve d, stop valve anc sequence valve 9.

When the condition which caused the preferred supply to fail has beenremedied and. voltage is restored thereto, the return of the load to thepreferred supply occurs as follows:

(6) Preferred voltage through micro-switch to will open control valve 15perrrg gas to ilow through the secondary gas supply system The flow orgas is controlled and directed to cause the ruins a 21 to move in adesired order.

(7) Gas pressure is immediately available to closed pilot valve 47 andpreferred Gas cannot pass through pilot valve 47 until sufficient timefilllplifiS (time delay) for gas to pass through variable oriile 45 andgas reservoir 46 and thence open pilot valve to permit flow of gasthrough it. Before pilot valve "*7 opens, the preferred ram 2% will moveupward tra n it g corresponding motion to close the attached switch l sin t preferred supply and parallel the sup lies.

(8) When pilot valve 47 opens, gas pressure becomes available to ram 21.The ram 21 will move downward transmitting corresponding motion to openthe attached switch lil in the emergency supply and separate thesupplies.

(9) As ram 21 approaches the end of its downward movement and openposition its attached mechanical actuator 3@ will momentarily contactknee action microswitch 13 and establish a pulse of preferred supplyvoltage to close control valve 15 and shut oil the gas at this point.

(10) The residual gas in the rams and gas lines beyond control valve 15will automatically vent to atmosphere through vents 96 in control valve15, and pilot valve d7. The apparatus is now reset to its normalposition and awaiting another condition causing failure of the preterredsupply.

Conditions pertaining to failure of both sources of supply A needlesstransfer of the load from the preferred supply to the emergency supplywill occur. Restoration of the load will depend on which source ofsupply first has voltage restored thereto.

Voltage restored first to emergency supply Voltage restored first topreferred source of supply The load cannot be restored to servicebecause the automatic transfer device is locked out by closed secondarygas valve 17. Automatic venting will occur at stop valve 16 and pilotvalve 7 when the preferred supply is restored. To restore the load tothe preferred supply it will then be necessary to perform manualoperations. The order of manual switching, as follows, of the switches100, 161

Imust be adhered to in order to avoid complete interruption it thecondition on the emergency supply has not been remedied: r

(l) Manually opens switch 101 in the emergency supply.

(2) Manually close switch in the preferred supply to restore the loadand load voltage to close gas valve 4 and open secondary gas valve 17.The apparatus is now reset to its normal position and awaiting anothercondition causing failure of the preferred supply.

The time delay means 48 as indicated in FIGURE 4 is used to assure fullmotion of preferred ram 20 before any motion of emergency ram 21. Thetime delayv means 48 may be replaced by a valve same as sequence valve 9if the valve is physically located so as to be opened when ram 2treaches the end of its upward stroke. If

i it is desired to have the preferred supply remain alive for apredetermined time before initiating transfer from emergency supplytopreferred supply, a time delay means similar to means 48 is requiredbetween control valve and ram 24).

FIGURE 5 The apparatus of FIGURE 5 is designed to enable automaticreturn by first opening switch 101 in the emergency supply and thenclosing switch it! in the preferred supply. Referring now to FIGURE 5,and assuming loss of load voltage associated with failure of thepreferred supply, the apparatus will function as follows:

(1) Gas valve 4 and'stop valve 16 will open permitting flow of gasthrough the main gas supply system 69. The flow of gas is controlled anddirected to cause the rams 2t) and 21 to move in a desired order.

(2) Gas pressure is immediately available to closed pilot valve 7 butgas cannot pass through it until suflicient time elapses (time delay)for gas to pass through variable orifice 5 and gas reservoir 6 andthence open pilot valve 7 to permit flow of gas through it. I

(3) When pilot valve 7 opens, gas pressure becomes available to closedsequence valve 9 and to preferred ram 26 attached to switch 130 in thepreferred supply. Ram

iluwill move downward transmitting corresponding motion to open theattached switch'ltlll in the preferred supply. When ram 20 reaches theend of its downward stroke, mechanical actuator 10 will cause sequencevalve 9 to open.

(4) When sequence valve 9 opens, gas pressure he comes available toemergency ram 21 attached to switch. 101 in emergency supply. Ram 21will move upward transmitting corresponding motion to close the attachedswitch lttl and restore load voltage to gas valve 4 and reenergize loadcircuit.

(5) Restoration of load voltage will cause gas valve 4 to close and shutoff the flow of gas. The residual gas in the cylinders and gas lines(beyond valve 4) will automatically vent to atmosphere through vents 99in pilot valve 7 and gas valve '4.

When the condition which caused the preferred supply to fail has beenremedied and voltage is restored thereto, the return of the load to thepreferred supply occurs as follows:

(6) Preferred supply voltage through micro-switch 12 will open controlvalve 15 permitting gas to flow through another gas supply system 105.The flow of gas is controlled and directed to cause the rams 20, 21 tomove in a desired order. As preferred supplying voltage becomesavailable to micro-switch 12, it also becomes available to close stopvalve 16.

(7) Gas pressure is immediately available to closed pilot valve 47. Gascannot pass through pilot valve 47 until sufiicient time elapses (timedelay) for gas to pass through variable orifice 45 and gas reservoir 46and thence open pilot valve 47 to permit flow of gas through (8) Whenpilot valve 47 opens, gas pressure becomes available to closed throwvalve 29 and to ram 21 attached to switch 101 in emergency supply. Ram21 will move downward transmitting corresponding motion to open theattached switch 101 in the emergency supply.

mentarily contact knee action micro-switch 23 and establish a pulse ofpreferred supply voltage to close control valve 15 and shut oil gas atthis point.

(11) The residual gas in the rams and gas lines (beyond control valve15) will automatically vent to atmosphere through vents in control valve15 and pilot valve 47. The apparatus is now reset to its normal positionand awaiting another condition causing failure of the preferred supply.

Conditions pertaining to failure of both sources of pp y A needlesstransfer of the load circuit from the preferred supply to the emergencysupply will occur. Restoration of the load circuit will depend on whichsource of supply first has voltage restored thereto.

Voltage restored first to emergency supply (1) The load circuit isimmediately restored and load voltage will cause gas valve 4 to close.The residual gas in the rams and gas lines beyond gas valve 4 willautomatically vent to atmosphere through vents 90 in valve 4 and pilotvalve 7 and the apparatus awaits restoration of voltage to the preferredsource of supply.

Voltage restored first to preferred supply (1) Upon restoration ofvoltage to the preferred supply, the apparatus will operate in items(6), (7), (8),

(9), (10) and (11) immediately above.

In the claims, the pilot valves 7 and '47 of the time delay means 8 and48 respectively are identified as threshold pressure valves for clarity.

The embodiments of the invention in which an exclusive property orprivilege is claimed are defined as follows:

I claim:

1. In electrical apparatus, an electrical load, an electrical preferredsupply, an electrical emergency supply,

switch means connected to said load and normally connecting said load tosaid preferred supply, transfer means connected to said switch means andresponsive to a predetermined condition of said preferred supply todisconnect said switch means from said preferred supply and to connectsaid switch means to said emergency supply, said transfer means havinga. fluid powered means for actuating said switch means, and wherein saidswitch means includes a preferred switch and an emergency switchengageable with the preferred supply and the emergency supplyrespectively; said fluid powered means including a gas driven preferredram and a gas driven emergency ram operably associated with theirrespective preferred and emergency switches, said transfer meansincluding a gas supply system operably associated with the ramsincluding a gas valve responsive to and openable upon loss of preferredvoltage to the load, to allow gas flow to said preferred ram to move theram and open said preferred switch, a sequence valve in said gas supplysystem responsive to the opening movement of said ram to enable gas flowto said emergency ram to move the ram and close said emergency switch.

2. In electrical apparatus as defined in claim 1 and wherein saidtransfer means includes a time delay means in said gas supply systemdownstream of said gas valve to delay preferred ram movement for apredetermined time period. v

3. In electrical apparatus as defined in claim 2 and wherein said timedelay means includes a by-pass line, a variable orifice valve followedby a gas reservoir followed by a threshold pressure valve which at apredetermined threshold pressure opens said by-pass line around theabove for gas flow to the rams.

4. In electrical apparatus as defined in claim 3 and wherein said gassupply system includes a vent valve downstream of said gas valve tofacilitate manual operation of the rams.

5. In a device for actuating a preferred switch and an emergency switchto change-over an electrical load rom a preferred supply to an emergencysupply in response to a predetermined condition, comprising transermeans having a fluid driven preferred ram adapted to be operablyassociated with said preferred switch and a fluid driven emergency ramadapted to be operably associated with said emergency switch, a main gassupply system operably associated With the rams including a main gasvalve upstream thereof responsive to and openable upon saidpredetermined condition to allow gas flow to said preferred ram to movethe ram to enable opening of the preferred switch, a sequence valve insaid gas supply system responsive to the opening movement of said ram toenable gas flow to said emergency ram to move the ram to enable closingof said emergency switch.

6. In a device in accordance with claim 5 and wherein said transfermeans includes a time delay means in said gas supply system downstreamof said gas valve to delay preferred ram movement for a predeterminedtime period.

7. In a device in accordance with claim 6 and wherein said time delaymeans includes a by-pass line, a variable orifice valve followed by agas reservoir followed by a threshold pressure valve which at apredetermined threshold pressure opens said by-pass' line around theabove for gas flow to the rams.

8' In a device in accordance with claim 7 and wherein said gas supplysystem includes a vent valve downstream of said gas valve to facilitatemanual operation of the rams.

9. In a device in accordance with claim 5 wherein said predeterminedcondition is a failure of load voltage and wherein said main gas supplysystem includes a stop valve upstream of said preferred ram normallyclosed and openable upon failure of preferred supply voltage, asecondary gas supply system for returning the rams to normal conditionincluding a secondary gas valve responsive to and openable upon failureof load voltage, a control valve downstream of said secondary gas valveresponsive to closing movement of said emergency ram and preferredsupply voltage to allow gas flow to said preferred ram to return the ramto ciosed position and to allow gas flow to said emergency ram to returnthe ram to open position, a secondary time delay means between saidcontrol valve and said emergency ram to delay gas flow to the ram untilthe preferred ram reaches closed position, said control valve beingresponsive to movement of the emergency ram to open position to stop gasflow.

10. In a device in accordance with claim 9 and wherein said main gassupply system includes a time delay means downstream of saidgas valveand said stop valve to delay preferred ram movement for a predeterminedtime period.

11. In a device in accordance with claim 5 wherein said predeterminedcondition is a failure of load voltage and wherein said main gas supplysystem includes a stop valve upstream of said preferred ram normallyclosed and openable upon failure of preferred supply voltage, anothergas supply system for returning the rams to normal condition including acontrol valve responsive to closing movement of said emergency ram andpreferred supply voltage to allow gas flow to said emergency ram toreturn the ram to open position, a throw valve between said another gassupply system and said preferred ram and openable in espouse to returnto open position by said emergency ram, said control valve beingresponsive to movement of the preferred ram to closed position to stopgas flow.

12. In a device in accordance with claim 11 and wherein said main gassupply system includes a time delay means downstream of said gas valveand said stop valve to delay preferred ram movement for a predeterminedtime period and wherein said another gas supply system includes anothertime delay means between said control valve and said throw valve.

13. In a device in accordance with claim 5 wherein said predeterminedcondition is a failure of load voltage and wherein said main gas supplysystem includes a stop valve 16 upstream of said preferred ram normallyclosed and openable upon failure of preferred supply voltage, asecondary gas supply system for returning the rams to normal conditionincluding a secondary gas valve responsive to and openable upon failureof load voltage, a control valve downstream of said secondary gas valveresponsive to closing movement of said emergency ram and preferredsupply voltage to allow gas flow to said preferred ram to return the ramto closed position and to allow gas flow to said emergency ram to returnthe ram to open position, means operatively associated with said controlvalve and said emergency ram to delay gas flow to the ram until thepreferred ram reaches closed position, said control valve beingresponsive to movement of the emergency ram to open position to stop gasflow.

References Cited in the file of this patent UNITED STATES PATENTS UNITEDSTATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,014, 136December 19 1961 Edward J. Leimkuhler It is hereby certified that errorappears in the above numbered patent requiring correction and that thesaid Letters Patent should read as corrected below.

Column 4, line 1, after "load" insert voltage o Signed and sealed this24th day of April 1962.

(SEAL) Attest:

ESTON G, JOHNSON DAVID L. LADD Attestihg Officer Commissioner of PatentsUNITED STATES PATENT OFFICE CERTIFICATE] OF CORRECTION Patent Noe3,014,13 7 December 19 1961 Edward J. Leimkuhler It is hereby certifiedthat error appears in the above numbered patent requiring correction andthat the said Letters Patent should read as corrected below.

Column 4, line 1, after "load" insert voltage Signed and sealed this.24th day of April 1962,

(SEAL) Attest:

ESTON (5,. JOHNSON I DAVID L. LADD Attesting Officer Commissioner ofPatents

